Photographic four-color light-sensitive stripping elements



Jan. 3, 1950 J, A BALL ET AL 2,492,954

PHOTOGRAPHIC FOUR-COLOR LIGHT-SENSITIVE STRIPPING ELEMENTS Filed Dec. 24, 1947 BLUE SENSITIVE GELATINO- SILVER BROMIDE EMULSION O- SULFOBENZALDEHYDE ACETAL OF Y'VINYL ALCOHOL AND YELLOW DYE LVER-IODOBROMIDE- SENSITIVE 5I4 I0 520 mu O-SULFOBENZALDEHYDE ACETAL OF POLYVINYL ALCOHOL CONTAINING WOOL ORANGE A GELATINO SILVER'IODOBROMIDE SENSITIVEfiTOmu O- SULFOBENZALDEHYDE ACETAL OF POLYVINYL ALCOHOL DYED CONGO RED SILVER-IODOBROMIDE-SENSITIVE I0 670 mu CELLULOSE ACETATE FILM BASE ANTIHALATION LAYER INVENTORS: JOSEPH ARTHUR BALL, ANDREW BRADSHAW JENNINGS and OTIS WILLARD MURRAY ATTORNEY Patented Jan. 3, 1950 UNITED STATES PATENT OFFICE PHOTOGRAPHIC FOUR-COLOR LIGHT- SENSITIVE STRIPPING ELEMENTS Joseph Arthur Ball, Los Angeles, Calif., Andrew Bradshaw Jennings, New Brunswick, N. J and Otis Willard Murray, Burbank, Calif., assignors to E. I. du Pont de Nemours & Company, 'Wilmington, Del., a corporation of Delaware Application December 24, 1947, Serial No. 793,724

3 Claims.

four differentially sensitized emulsion layers,

three of which can be stripped from the support during processing.

An object of this invention is to provide new photographic elements which are useful in processes of four-color photography. Another object is to provide such elements which can be used to readily obtain four individual color records. A further object is to provide a monopack film element with four difierentially sensitized layers from which four color records can be easily separated and processed individually. A still further object is to provide novel processes for obtaining color separation records from such elements. Still other objects will be apparent from the following description of the invention.

The novel photographic elements of this invention consist of a support, such as a transparent film base, provided with a stratum of non-halation material having superposed on one side thereof in order (a) a hydrophilic colloidsilver halide emulsion layer which is sensitive to light in the red region of the spectrum having strong sensitivity in the 605 to 670 millimicron region; (b) a stripping separator layer which preferably contains a small amount of a light filter dye for layer (a); (c) a hydrophilic colloid silver halide emulsion layer which is sensitive to green light possessing its maximum sensitivity between 545 and 575 millimicrons; (d) a stripping layer containing a filter dye to which the next layer (e) is effectively sensitive; (e) a hydrophilic colloid-silver halide emulsion layer which has an extra range of strong sensitivity at 490 to 535 millimicrons; (f) a stripping layer containing a yellow filter dye or pigment; and, finally, (g) a hydrophilic colloid-silver halide emulsion layer which is sensitive to blue and violet light only.

It is to be understood that each of the silver halide emulsion layers are inherently sensitive to blue light, in addition to having the extra sensitivity specified above. However, the light filter layers prevent the lower layers from being exposed in the blue region of the spectrum.

The novel photographic elements of this invention are especially useful in the processes of four-color photography disclosed in Ball application Serial Number 771,790, filed September 2, 1947. The photographic elements can be used I to form four individual color separation records from which four color separation positive silver image records can be printed as provided in said application. The latter image records can then be converted into colored images having the absorption peaks and characteristics taught in said application. The colored images may then be superposed in register to reproduce a multicolor picture.

The stripping layers of the elements may be composed of various materials which are softened or dissolved by water. Thus, the may be composed of any water-soluble colloid (viz. which has a marked solubility in water at 20 C.) of natural or synthetic type. Suitable colloids water-soluble cellulose derivatives, e. g., low substituted cellulose ethers, such as methyl cellulose, ethyl cellulose, and bezyl' cellulose, cellulose esters having solubilizing acid salt groups, e. g., sodium, potassium, and ammonium salts of cellulose acid phthalate, cellulose ether acids, e. g., sodium cellulose glycollate, casein gelatin mixtures, water-soluble synthetic resins, e. g., polyvinyl alcohol and esters.

In the preferred aspect of the invention, the stripping layers are composed of a water-soluble but photographic alkaline developer insoluble colloid. Preferred colloids of this type are composed of water-soluble macromolecular acetals of vinyl alcohol polymers with an aldehyde containing sulfonic acid and/or carboxylic acid groups or their water-soluble salts, e. g., alkali metal, ammonium or amine salts.

The water-soluble macromolecular acetals can be made by the reaction of a vinyl alcohol polymer, including interpolymers, with an aldehyde containing a sulfonic acid or a carboxylic acid group under acetal-forming conditions. For example, the acetalization may be conveniently carried out in solution or suspension in water 'or an organic solvent or diluent using a catalyst such as phosphoric acid, sulfuric acid, hydrochloric acid, etc. Suitable procedures and aldehydes are described in United States Patent 2,310,943 and in German Patent No. 643,650. The free acid groups can be converted into salt groups include 3 by a simple neutralization as described above and in the United States patent.

Partiall and completely hydrolyzed polyvinyl alcohols of low, intermediate, and high viscosity, having a molecular Weight of 5,000 to 50,000 and hydrolyzed interpolymers of vinyl esters with one or less equivalent of a terminally unsaturated interpolymerizable organic compound can be used in preparing the vinyl alcohol acetals of aldehydes containing carboxylic or sulfonic acid groups. In general, such polymers having for each 100 carbon atoms between and 50 free non-phenolic hydroxyl groups are useful.

Preferred water-soluble, macromolecular, neutralized acetals of vinyl alcohol polymers used in accordance with this invention are prepared by acetalization from (1) polyvinyl alcohol of high molecular weight (viscosity of 4% aqueous'solution at 20 C., 40 to 60 centipoises), (2) polyvinylalcohol of medium molecular: weight (viscosity of 4% aqueous solutions at 20 C., 15 to centiposies) substituted on to 60% of the hydroxyl groups with acetate, propionate; acetal, propional, and butyral groups, 75 to 100% hydrolyzed interpolymers of vinyl acetate with 0.05 to 0.5 mol equivalents of terminally unsaturated monoolefin's, e. g., ethylene, such as described in Roland. United States Patent No. 2,386,347, and (4) completel'yhydrol'yzed interpol'ymers of vinyl acetate with minor portion (less than of polymerizable vinyl or vinylidene compounds, for example, vinyl-chloride, vinyl cyanide, alkyl methacrylates, e; g., methyl and ethyl methacrylate, etc., with an aldehyde containing carb'cix'ylic or a sulfonic acid group.

The preierre'd'polyvinyl a'cetals'have the above properties and, in addition, are colorless or substantially colorless and are free from color former nuclei.

The degree of substitution of the acetal groups may vary over a wide range. Thus, vinyl alcohol polymers having between 5 and of the hydroxyl groups acetalized with. acidic aldehydes have been found useful. However, it. has been. found. that the best" results are obtained when between 10 and 35% of thehydroxyl groups are acetalized with the acidic aldehydes. The total. acetal content based on these figures will vary depending on the hydroxyl content of the polymer, but it has been found that the best results are obtained when between 5 and 17-'%, of the carbon atoms of the polymer chain contain the acetal groups with COO- and SO3.- radicals. The acetals having. this degree. of substitution, however, may be used inthe form of the free acids butare preferably used in the formof the watersoluble salts which are soluble to the extent. of at least 5% at temperatures below 30 C. in methanol or ethanol containing up to 20% of water.

While any aldehyde containing a free carboxylic or sulfonic acidradicalmay be used in preparing these acetals, those having amolecular weight ofless than 200 are preferred as, in gen- 7 eral, they react more readily and completely. These aldehyde-acids may bearomatic, aliphatic, or mixed aromatic-aliphatic.

The colloid stripping materials,.e..g., the watersoluble macromolecular. acetals of vinyl alcohol polymers described above can be applied to the contiguous layer from a solution or dispersion inthe same general manner that gelatin overcoatings are applied. The aceta-l layers soapplied should be of such a thickness that they maybe readily stripped from the. layer on which they.

are coated. The exact thicknesses can be readily determined by experiment. Thicknesses of 0.0001 to 0.0005 inch, in general, are satisfactory. Materially thinner layers, e. g. 0.05 to 2.0 microns, in general, adhere quite firmly. They may be applied from aqueous or organic solvent solutions. Useful solvents are the water-soluble alcohols, e. g., methanol, ethanol, acetone, dioxane, etc. Mixtures of such solvents with water are quite useful. The coating solutions are preferably substantially neutral. Their pHican be adjusted by neutralizing the free acid groups with bases capable of yielding water-soluble salts, e. g. alkali metals, ammonia, and amines. Various filter dyes or pigments are added to the coating solutions prior to depositing the layers on the silver halide emulsion layers.

In'using the novel film elements, the emulsion surface isplacednearest to the lens in the camera and. itis then exposed to a multicolor object .field. The exposed: film is then developed in an alkaline photographic developing bath whereby fou'r colbr separat'ion negative silver image records are formed in the respective layers of the monopack element. It is then treated in an acid stop bath. The film element. is thenimmers'edin a' water'batli' whereby the bond'between.

the image bearing layers. and the water soluble colloid weakens or dissolves". The: image bearing. layers are successively removediand can. be individually treated. They" may,, for examplebe fixed, washed, and" dried resulting in four developed color separation negatives suitable for registration. printing on. separate film. elements to' produce positives on which exposed film' elements can be color developed inithe' appropriate bath to form a. dye image of the proper color in situ with a silver image as described in aforesaid Ball application; The silver. and silversalts are removed-leavinga dye image. The four dye image positiverecordsare s'uperposed'in register which results in a' multicolor positive picture;

Thein'vention' willbe further illustrated by the folltiwing example;

Example,

A- cellulose acetate base is coated on its rear surface with: an antihalafion layer composed o'f:o-sulfobenzaldehydeacetal 0f polyvinylal'cohol and finel'y divided orcomminutesilver. The frontsurface isth'en provided in order with the-following seven layers-andhaving-the construction set forth" in Fig. 1 0fthe accompanying drawing which forms part of thisspecification. Layer l isa gelatino-silver iodobromide' emulsion layer having a coating-weightof 50 milligrams of silver bromide per square d'ecimeter andcontaining 1,1-diethyl 2,2-carbocyanine iodide which confers sensitivity to about 670 mil1imi'crons.

Layer 2 is composed of a water-soluble, de-

veloper insoluble'o sulfobenzaldehyde' acetalof sion havinga coating weightlikezlayer; l and containing 3,3-:diethyl+9-.methyl zoxycarbocyanine iodideiand has a maximum sensitivity at 514 to 520 millimicrons.

Layer 6 is smilar to layer 2 but contains Tartrazine-Q (Colour Index No. 640 in place of Congo Red.

Layer 1 is a blue-sensitive =gelatino-silver iodobromide .emulsion having 'a coating weight of 50 milligrams of silver bromide per. square decimeter.

The film is exposed in a camera to a natural multicolor scene 2.1101115 thenzdeveloped for seven minutes in a solution of the following composition:

Hydroquinone grams.- 27.5 p-N-methylaminophenol sulfate do :0 Sodium sulfite (anhydrous) do 60.0 Sodium carbonate (anhydrous) do 50.0 Potassium bromide do 15.0 Water to liters 1.0

The developed film is then treated for one minute in a stop bath of the composition:

The outer layer I is then pressed into intimate contact with a second registered support comprising a transparent film base coated with a gelatin layer having a coating weight of about 75 milligrams of silver bromide per square decimeter which had been wetted with water to promote adhesion between the gelatin surfaces. The water weakens the bond of layer 8 whereby layer 1 is stripped from the element.

It is possible to alter the time of immersion in the stop bath and the state of water absorption of the gel blank so that the outermost image layer may be removed without weakening the adhesion of the under layers.

Layers 5 and 3 are transferred to separate film elements bearing gelatin layers in like manner. By reimmersion in the stop bath and bringing into contact with other wetted blanks, the remaining layers may be successively transferred, in each case regulating the time of immersion and water content of the blank so as to remove only the desired layer. The resulting four separate color separation records are fixed, washed, and dried and used to print onto positive film elements which can be color developed, fixed, washed, and dried as described in the aforedescribed Ball application.

A similar element can be made by substituting for the yellow filter material of layer 6 other dyes or pigments including Auramine 0 (Color Index No. 655), Quinoline Yellow (Color Index No. 801), Naphthol Yellow S (Color Index No. 10), and yellow colloidal silver.

Inert salts, e. g., sodium sulfate (about 120 grams per liter) can be added to the stop baths to prevent excessive softening of the stripping layer if desired.

Similarly in place of the sensitizing dyes for layer I, there may be substituted 3,3-diethyl selenacarbocyanine iodide or 2 (p-dimethylaminostyryl 6 ethoxybenzothiazole ethyl bromide. Additional sensitizing dyes suitable for layer 3 include 3 ethyl 5(3-ethyl-2(3) -benzoxazolylidene) ethylidene-rhodanine and 1,1'-diethyl pseudocyanine-p-toluene sulfonate. In place of the sensitizers for layer 5, there can be used 3,3-

:diethyl-aoxycarbocyaninenziodide.:or 3,3ediethyl- -5,5'-di-methy1oxycarbocyanine iodide.

' "In placeofthe filterdyes forlayerA, therecan be used "Bontacyl' Brilliant Orange 2R,-Colour Indexl#21-7 6, and Lake Scarlet R, Colour Index 79. Various other-stripping layers can-lbe used in place of thespecificiacetal of the example. They may "be composed 'of any of the materials described above for this purpose.- Additional suitable coating compositions for this purpose include the following:

Solution A Casein ;;;grams 20.!) Water s l i cc 100.0 'NazCOz (20%) cc 6.8 Gelatin .-grams 1.0 Mannitan monolaurate (10%) cc 5&0 Water cc 50.0

Solution B Corn dextrine grams-.. 10.0 Water cc 100.0 Ethanol cc 20.0 Saponin solution cc 10.0 Sodium dodecyl sulfate (10%) cc 2.0 SolutionC Cellulose acetate-acid phtha1ate grams 5.0 NazCOa cc-.. 10.0 Water cc 150.0 Ethanol cc 50.0 Gelatin grams 5.0 Water cc 100.0

SoZutz'on'D Cellulose acetate (17% acetyl content) "grams" 10.0 Water cc 1000.0

It is to be understood, however, that the lightscreening or filter dyes or pigments are to be added to said solutions before coating.

The silver halide emulsion layers are preferably composed of gelatin as the binding agent. However, various other natural or synthetic hydrophilic colloids can be used, if desired, e. g., agar agar, albumen, nylon, polyvinyl acetals, the hydrolyzed ethylene/vinyl acetate interpolymers of Patent No. 2,397,866, etc.

An advantage of the invention resides in the fact that it provides a novel and practical unitary element for four-color photography. A further object is that the element can be made in a simple and. economical manner. A further advantage is that it is unitary and offers no difiiculty in fitting it to cameras. It can be readily processed to yield four-color separation records which can be separately handled.

What is claimed is:

1. A multilayer photographic element comprising a transparent film base having superposed thereon in order a hydrophilic colloid silver halide emulsion layer which has an extra band of sensitivity in the red region of the spectrum with a maximum sensitivity at a position within the range from 605 to 670 millimicrons, a stripping separator layer composed of a developer-insoluble, water-soluble colloid containing a light-filter dye for the aforesaid first layer, a hydrophilic colloid silver halide emulsion layer which has an extra band of sensitivity in the yellow region of the spectrum with a. maximum sensitivity at a position within the range 545 to 575 millimicrons, a stripping layer composed of a developer-insoluble, water-soluble colloid containing a filter dye which absorbs light to which the next-mentioned layer is eitectivelyjensitivri hydrophilic colloid silver halide emulsion which has an extra band of sensitivity in the green region of the spectrum with a maximum sensitivity at a position between 490rand 535 millimicrons. a stripping layer composed of a developer-insoluble, watersoluble colloid containing a yellow filter material and finally a. hydrophilic colloid silver halide emulsion layer which is sensitive to blue light only. x

2. An element as set forth in claim 1 wherein the hydrophilic colloid is gelatin.

3. An element as set forth in claim 1 wherein said silver halide emulsion layers contain gelatin as the binding agent and the stripping layers are composed of a water-soluble acetal of a vinyl alcohol polymer with an aldehyde containing a group taken from the class consisting of free calboxylic acid groups, free sulionic acidgroups, and their water-soluble salts. w

JOSEPH ARTHUR BALL. ANDREW BRADSHAW JENNINGS. OTIS WILLARD MURRAY.

REFERENCES CITED The following references are of record in the me of this patent:

UNITED STATES PATENTS 

1. A MULITILAYER PHOTOGRAPHIC ELEMENT COMPRISING A TRANSPARENT FILM BASE HAVING SUPERPOSED THEREON IN ORDER A HYDROPHILIC COLLOID SILVER HALIDE EMULSIOIN LAYER WHICH HAS AN EXTRA BAND OF SENSITIVITY IN THE RED REGION OF THE SPECTRUM WITH A MAXIMUM SENSITIVITY AT A POSITION WITHIN THE RANGE FROM 605 TO 670 MILLIMICRONS, A STRIPPING SEPARATOR LAYER COMPOSED OF A DEVELOPER-INSOLUBLE, WATER-SOLUBLE COLLOID CONTAINING A LIGHT-FILTER DYE FOR THE AFORESAID FIRST LAYER, A HYDROPHILIC COLLOID LAYER HALIDE EMULSION LAYER WHICH HAS AN EXTRA BAND OF SENSITIVITY IN THE YELLOW REGION OF THE SPECTRUM WITH A MAXIMUM SENSITIVITY AT A POSITION WITHIN THE RANGE 545 TO 575 MILLIMICRONS, A STRIPPING LAYER COMPOSED OF A DEVELOPER-INSOLUBLE, WATER-SOLUBLE COLLOID CONTAINING A FILTER DYE 